3_Other_node_tree_representations.markdown

Other node tree representations

It is possible to convert the AST into several textual representations, which serve different uses.

Simple serialization

It is possible to serialize the node tree using serialize() and also unserialize it using unserialize(). The output is not human readable and not easily processable from anything but PHP, but it is compact and generates fast. The main application thus is in caching.

Human readable dumping

Furthermore it is possible to dump nodes into a human readable format using the dump method of PhpParser\NodeDumper. This can be used for debugging.

$code = <<<'CODE'
<?php

function printLine($msg) {
    echo $msg, "\n";
}

printLine('Hello World!!!');
CODE;

$parser = (new PhpParser\ParserFactory)->create(PhpParser\ParserFactory::PREFER_PHP7);
$nodeDumper = new PhpParser\NodeDumper;

try {
    $stmts = $parser->parse($code);

    echo $nodeDumper->dump($stmts), "\n";
} catch (PhpParser\Error $e) {
    echo 'Parse Error: ', $e->getMessage();
}

The above script will have an output looking roughly like this:

array(
    0: Stmt_Function(
        byRef: false
        params: array(
            0: Param(
                name: msg
                default: null
                type: null
                byRef: false
            )
        )
        stmts: array(
            0: Stmt_Echo(
                exprs: array(
                    0: Expr_Variable(
                        name: msg
                    )
                    1: Scalar_String(
                        value:

                    )
                )
            )
        )
        name: printLine
    )
    1: Expr_FuncCall(
        name: Name(
            parts: array(
                0: printLine
            )
        )
        args: array(
            0: Arg(
                value: Scalar_String(
                    value: Hello World!!!
                )
                byRef: false
            )
        )
    )
)

Serialization to XML

It is also possible to serialize the node tree to XML using PhpParser\Serializer\XML->serialize() and to unserialize it using PhpParser\Unserializer\XML->unserialize(). This is useful for interfacing with other languages and applications or for doing transformation using XSLT.

<?php
$code = <<<'CODE'
<?php

function printLine($msg) {
    echo $msg, "\n";
}

printLine('Hello World!!!');
CODE;

$parser = (new PhpParser\ParserFactory)->create(PhpParser\ParserFactory::PREFER_PHP7);
$serializer = new PhpParser\Serializer\XML;

try {
    $stmts = $parser->parse($code);

    echo $serializer->serialize($stmts);
} catch (PhpParser\Error $e) {
    echo 'Parse Error: ', $e->getMessage();
}

Produces:

<?xml version="1.0" encoding="UTF-8"?>
<AST xmlns:node="http://nikic.github.com/PHPParser/XML/node" xmlns:subNode="http://nikic.github.com/PHPParser/XML/subNode" xmlns:scalar="http://nikic.github.com/PHPParser/XML/scalar">
 <scalar:array>
  <node:Stmt_Function line="2">
   <subNode:byRef>
    <scalar:false/>
   </subNode:byRef>
   <subNode:params>
    <scalar:array>
     <node:Param line="2">
      <subNode:name>
       <scalar:string>msg</scalar:string>
      </subNode:name>
      <subNode:default>
       <scalar:null/>
      </subNode:default>
      <subNode:type>
       <scalar:null/>
      </subNode:type>
      <subNode:byRef>
       <scalar:false/>
      </subNode:byRef>
     </node:Param>
    </scalar:array>
   </subNode:params>
   <subNode:stmts>
    <scalar:array>
     <node:Stmt_Echo line="3">
      <subNode:exprs>
       <scalar:array>
        <node:Expr_Variable line="3">
         <subNode:name>
          <scalar:string>msg</scalar:string>
         </subNode:name>
        </node:Expr_Variable>
        <node:Scalar_String line="3">
         <subNode:value>
          <scalar:string>
</scalar:string>
         </subNode:value>
        </node:Scalar_String>
       </scalar:array>
      </subNode:exprs>
     </node:Stmt_Echo>
    </scalar:array>
   </subNode:stmts>
   <subNode:name>
    <scalar:string>printLine</scalar:string>
   </subNode:name>
  </node:Stmt_Function>
  <node:Expr_FuncCall line="6">
   <subNode:name>
    <node:Name line="6">
     <subNode:parts>
      <scalar:array>
       <scalar:string>printLine</scalar:string>
      </scalar:array>
     </subNode:parts>
    </node:Name>
   </subNode:name>
   <subNode:args>
    <scalar:array>
     <node:Arg line="6">
      <subNode:value>
       <node:Scalar_String line="6">
        <subNode:value>
         <scalar:string>Hello World!!!</scalar:string>
        </subNode:value>
       </node:Scalar_String>
      </subNode:value>
      <subNode:byRef>
       <scalar:false/>
      </subNode:byRef>
     </node:Arg>
    </scalar:array>
   </subNode:args>
  </node:Expr_FuncCall>
 </scalar:array>
</AST>